Discrete-time Adaptive SMO based Sensorless Fixed-Switching-Frequency MPC of Three-Level NPC-fed PMSM Drives

This paper presents a discrete-time sliding-mode observer (SMO) based sensorless model predictive control (MPC) method for three-level neutral-point-clamped (NPC) inverter-fed permanent magnet synchronous motor (PMSM) drives. The fixed-switching-frequency model predictive current control (MPCC) features higher dynamics, lower dv/dt as well as superior harmonic spectra, which is suitable for high-performance drive applications. To achieve superior rotor position estimation accuracy and dynamic with sensorless MPC, a discrete-time domain designed adaptive SMO is proposed to avoid approximation. The optimized voltage references regulated by the MPCC process can be directly used for EMF estimation. Furthermore, the adaptive filter by adopting multiple second-order generalized integrator (SOGI) structures is adopted to filter out the low harmonics in estimated EMF waveforms. Therefore, the inevitable estimation error and delay caused by conventional low pass filter (LPF) can be eliminated. The simulation and experimental results are provided to verify the effectiveness of the proposed method.